Most of the surfaces of our cells are covered with sugar chains. It is known that viruses recognize sugar chains existing on the surface of a cell, bind and migrate into cells, and infect the cells. The infection of viruses into higher animals or plants causes diseases. Often, the infectious viruses tend to infect the same species of animals or plants. For example, avian influenza viruses regularly do not infect human except for the case of the mutation of viral RNA. In cases of domestic animals, agricultural crops, and ornamental animals or plants, viruses that are capable of infecting such animals or plants are transmitted among the same species, causing damages in the production. Therefore, identification of viruses, bacteria etc. capable of infecting such animals or plants is essential for sensitive diagnosis, which contributes to the determination of the early treatment or prevention.
The inventors of the present invention have aimed to provide a method for concentrating target viruses etc. from a specimen containing a number of contaminants and for identifying the concentrated viruses in a short time, and have succeeded in developing a concentration method using sugar chain-immobilized metal nano-particles prepared by immobilizing to a metal a ligand-conjugate, in which a sugar chain is connected with the well-designed linker compound having a predetermined structure, and by using sugar chain linkages of viruses etc. (Japanese Patent Application Publication, Tokukai, No. 2009-148246 A (publication date: Jul. 9, 2009)) based on the binding interaction between sugar chains and viruses.
The size of viruses is approximately 100 nm, and recovery and concentration of viruses is generally carried out by high-speed centrifugation such as ultracentrifugation.
However, in the ultracentrifugation, an extremely large gravity has to be applied to a sample. Consequently, due to uneven balance in weight between samples, there would be a danger such as scattering of the samples. Since such scattering of samples must be avoided, there has been requested a method for concentrating viruses without using centrifugation. Similarly, also in a case of concentrating cells or bacteria, there has been requested a method for concentrating cells or bacteria without using centrifugation in order to avoid the aforementioned danger.